One or more probes, which protrude into the exhaust gas flow volume of the exhaust gas duct system for interaction with the exhaust gases, are frequently provided in exhaust gas duct systems removing combustion waste gases from an internal combustion engine for detecting the composition of the combustion waste gases, for example, in an upstream area of said exhaust gas duct systems. The exhaust gas duct system is, in general, open towards the outside in its downstream end area, so that it is possible, in principle, that liquid, e.g., water, will enter this downstream end area of the exhaust gas duct system. If the water reaches the area of the probes, the latter may be damaged. Since the output signals of such probes, which signals represent the exhaust gas composition, are also used to actuate, for example, an internal combustion engine in order to make it possible to reach the lowest possible pollutant emission, a loss of function or malfunction in the area of the probes may lead to a corresponding impairment in the operation of an internal combustion engine or other system areas of a vehicle.